Thermal death kinetics in eggs and larvae of Bactrocera latifrons (Diptera: Tephritidae) and comparative thermotolerance to three other tephritid fruit fly species in Hawaii.
Eggs, 1st-, and 3rd-instar larvae of Bactrocera latifrons were subjected to hot water immersion to determine thermal death kinetics. All stages exhibited nonlogarithmic death (survival) curves that were characterized by an initial lag in mortality followed by increasing death rates with time at a prescribed temperature. Increasing temperatures reduced the time necessary to kill 90 or 99% of insects for a given development stage. Arrhenius plots of the death rate function (k) showed a reduced slope for 3rd-instars compared to eggs or 1st-instars. Based on calculation of estimated lethality times needed for 90 or 99% mortality, eggs were more resistant to heat than 1st-instars at lower temperatures but were more susceptible at higher temperatures. Comparison of thermal death kinetics of B. latifrons with other tephritid fruit flies present in Hawaii revealed this species to be more resistant to heat than either Mediterranean fruit fly (C. capitata), oriental fruit fly (B. dorsalis) or melon fly (B. cucurbitae) using this bioassay. The results are discussed in relation to the use of heat treatments for disinfestation of tephritid fruit flies from agricultural commodities and the need for an international database to facilitate comparisons among these and other economically important tephritids, which could become pests in areas where they do not currently exist.